4 ms·

Other than standardizing on equipment and root certificates, none of this is new technology. The challenge is how do you revoke a certificate which was used to

Other than standardizing on equipment and root certificates, none of this is new technology. The challenge is how do you revoke a certificate which was used to issue millions of ID cards/passports once it leaks? Does everybody suddenly not have a "valid" ID proof? Or how do you scale non-digitized operations up on-demand once some of this fails? When it comes to privacy, government can even not keep any of the PII in a central place: it just needs to get it for signing and never needs to store it. Basically, you can have a device that wirelessly transmits government-signed data containing your facial data and other PII, and upon validation, that data would be used for facial recognition and ID verification. (Like JWT tokens for those familiar with them)

sureIy 2y ago
What certificate are you talking about? The document is your face
- gruez 2y ago
  "Your face" doesn't tell border officials anything important about you. For that, you need a travel document with relevant biographical information (eg. name, date of birth), along with a picture of your face so they know who to associate that information with. Finally, to ensure that you can't make a fake document that looks like a real document, there's a PKI system where all the information on the document is digitally signed by the country issuing the travel document.
  - deleted 2y ago
    [deleted]
  - sureIy 2y ago
    That's far down the line. The examples in the article just store the document data in national database. In both examples (Finland and Singapore) you register online before the trip and then still show up with your passport. Singaporeans just show up with their face because their face is already linked to their government ID, stored locally. This can be done by any country after pre-registering your regular passport. All of this is trivial to implement. There's still no mention of full digital validation.
    - Muromec 2y ago
      Well, the thing is -- after doing the whole ICAO PKI into the passport (which already happened) and keeping the trace in the local government database somebody realised there is no point to issue an expensive unforgable paper copy of it, since the digital artifact bundled with it (theoretically) provides stronger security. So instead of issuing ICAO PKI into the paassport, you can just have a dumb app generating a QR code with it or A4 paper extract.
- mhandley 2y ago
  How does that work for identical twins?
  - Muromec 2y ago
    The same way as it does now. The face is checked against the identity claim, not against the global lookup, which can't reliably work anyway.
    - timewizard 2y ago
      So there's no non-repudiation making it no different than a paper document.
      - Muromec 2y ago
        Sorry I can’t really parse the comment, but I do agree it’s no different from a paper document, because why would it?
  - BurningFrog 2y ago
    It's hard to think of any scheme that fully works for that, unless you mandate distinctive body modification like tattoos or scars.
out_of_protocol 2y ago
> how do you revoke a certificate which was used to issue millions of ID cards/passports once it leaks? Does everybody suddenly not have a "valid" ID proof? You need cutoff date and some kind of public trail log to prevent backdating new certificates. This can be done via short-lived secondary certs derived from a root one, logged publicly
- trilbyglens 2y ago
  Sounds a lot like a blockchain
  - gruez 2y ago
    It really isn't, aside from using public key cryptography. There isn't even a concept of a "block" (ie. a linked list where each node is cryptographically linked to a prior node).
  - out_of_protocol 2y ago
    Blockchain can be the store of public data (dump public keys of intermediate certs into blockchain), but it's not necessary, public trail log is enough to call on backdated cert issuing
- Muromec 2y ago
  That's pretty much how it works now, except they are not logged publicly.
- quotemstr 2y ago
  > You need cutoff date and some kind of public trail log to prevent backdating new certificates. You might be able to do it without a public log by using an RFC 3161 (TSP) secure timestamp facility like the unfortunately named https://www.freetsa.org/ https://www.freetsa.org/. Basically, we want to trust identity attestations ("I am Bill Clinton and this is my face") made by a compromised CA between the time the CA certificate was created and an estimate (hopefully a conservative one) of the date of compromise. We want to distrust any certificates signed outside this time range. This way, in the event of a CA compromise, we don't have to revoke everyone's certificate after a CA compromise. I think we can implement this security model by having the CA ask the TSP server to countersign each certificate that the CA issues. The TSP would sign a hash of the whole CSR, including both identity ("I am Bill Clinton") and biometric (bill-clinton.jpg) information. Anyone can use the TSP's attestation to provide that the TSP server witnessed this combination of inputs at a specific time. Sure, if you've compromised the CA, you can issue a certificate saying "I am Bill Clinton", but to do so, you need to either use a genuine, up-to-date TSP attestation, giving away the game, or you need to use an old TSP attestation, forcing you to use exactly the original inputs to the TSP. Using the exact inputs wouldn't help you: you want to issue a certificate saying "I am Bill Clinton" with attacker.jpg as the face, not bill-clinton.jpg. The latter won't help you do anything: you don't look like Bill Clinton and you don't have his private key. An attacker would have to compromise both the CA and the TSP server to pull off a passport forgery. And you can make this process even harder by requiring multiple independent TSP servers to countersign certificates.
layer8 2y ago
> The challenge is how do you revoke a certificate which was used to issue millions of ID cards/passports once it leaks? Does everybody suddenly not have a "valid" ID proof? Revocations always come with a revocation date. Only passports issued after that date would be invalidated. The issuance dates could be proofed with cryptographic timestamps. There is a trade-off between false positives and false negatives when choosing the revocation date of the issuer certificate. With OCSP, you could also revoke all the individual IDs that are not known-good (known to have been issued legitimately). Of course, a world-wide interoperable passport scheme is unlikely to be designed with such an elaborate verification system, and maintaining registries of all legitimate IDs comes with its own risks. In case of a massive breach, it’s more likely that everyone will have to get a new passport and re-prove their identity for that using separate means.
- xvilka 2y ago
  > In case of a massive breach, it’s more likely that everyone will have to get a new passport and re-prove their identity for that using separate means. If you have a big family with the ownership of many assets - a car, house or an apartment, bank accounts, mortgage, various subsidies, and so on, the number of instances that you need to go to change your old passport data to a new one could quickly grow up to one hundred, depending on a country. The biggest problem with reissuing a passport is that its number and issuance date change, forcing you to jump through many hoops to continue life as before.
  - jltsiren 2y ago
    That sounds weird. Which country abuses passports like that? From my perspective, a passport is just an identity document. It's not a source of identity. When you get a new passport, your identity doesn't change, so you don't have to update your information anywhere. Immigration officials may be the main exception, if you live outside the country of your citizenship. Or maybe there is some hassle if you need to transfer a visa to the new passport.
    - Joker_vD 2y ago

sureIy 2y ago

What certificate are you talking about? The document is your face

gruez 2y ago
"Your face" doesn't tell border officials anything important about you. For that, you need a travel document with relevant biographical information (eg. name, date of birth), along with a picture of your face so they know who to associate that information with. Finally, to ensure that you can't make a fake document that looks like a real document, there's a PKI system where all the information on the document is digitally signed by the country issuing the travel document.
- deleted 2y ago
  [deleted]
- sureIy 2y ago
  That's far down the line. The examples in the article just store the document data in national database. In both examples (Finland and Singapore) you register online before the trip and then still show up with your passport. Singaporeans just show up with their face because their face is already linked to their government ID, stored locally. This can be done by any country after pre-registering your regular passport. All of this is trivial to implement. There's still no mention of full digital validation.
  - Muromec 2y ago
    Well, the thing is -- after doing the whole ICAO PKI into the passport (which already happened) and keeping the trace in the local government database somebody realised there is no point to issue an expensive unforgable paper copy of it, since the digital artifact bundled with it (theoretically) provides stronger security. So instead of issuing ICAO PKI into the paassport, you can just have a dumb app generating a QR code with it or A4 paper extract.
mhandley 2y ago
How does that work for identical twins?
- Muromec 2y ago
  The same way as it does now. The face is checked against the identity claim, not against the global lookup, which can't reliably work anyway.
  - timewizard 2y ago
    So there's no non-repudiation making it no different than a paper document.
    - Muromec 2y ago
      Sorry I can’t really parse the comment, but I do agree it’s no different from a paper document, because why would it?
- BurningFrog 2y ago
  It's hard to think of any scheme that fully works for that, unless you mandate distinctive body modification like tattoos or scars.

out_of_protocol 2y ago

> how do you revoke a certificate which was used to issue millions of ID cards/passports once it leaks? Does everybody suddenly not have a "valid" ID proof? You need cutoff date and some kind of public trail log to prevent backdating new certificates. This can be done via short-lived secondary certs derived from a root one, logged publicly

trilbyglens 2y ago
Sounds a lot like a blockchain
- gruez 2y ago
  It really isn't, aside from using public key cryptography. There isn't even a concept of a "block" (ie. a linked list where each node is cryptographically linked to a prior node).
- out_of_protocol 2y ago
  Blockchain can be the store of public data (dump public keys of intermediate certs into blockchain), but it's not necessary, public trail log is enough to call on backdated cert issuing
Muromec 2y ago
That's pretty much how it works now, except they are not logged publicly.
quotemstr 2y ago
> You need cutoff date and some kind of public trail log to prevent backdating new certificates. You might be able to do it without a public log by using an RFC 3161 (TSP) secure timestamp facility like the unfortunately named https://www.freetsa.org/ https://www.freetsa.org/. Basically, we want to trust identity attestations ("I am Bill Clinton and this is my face") made by a compromised CA between the time the CA certificate was created and an estimate (hopefully a conservative one) of the date of compromise. We want to distrust any certificates signed outside this time range. This way, in the event of a CA compromise, we don't have to revoke everyone's certificate after a CA compromise. I think we can implement this security model by having the CA ask the TSP server to countersign each certificate that the CA issues. The TSP would sign a hash of the whole CSR, including both identity ("I am Bill Clinton") and biometric (bill-clinton.jpg) information. Anyone can use the TSP's attestation to provide that the TSP server witnessed this combination of inputs at a specific time. Sure, if you've compromised the CA, you can issue a certificate saying "I am Bill Clinton", but to do so, you need to either use a genuine, up-to-date TSP attestation, giving away the game, or you need to use an old TSP attestation, forcing you to use exactly the original inputs to the TSP. Using the exact inputs wouldn't help you: you want to issue a certificate saying "I am Bill Clinton" with attacker.jpg as the face, not bill-clinton.jpg. The latter won't help you do anything: you don't look like Bill Clinton and you don't have his private key. An attacker would have to compromise both the CA and the TSP server to pull off a passport forgery. And you can make this process even harder by requiring multiple independent TSP servers to countersign certificates.

layer8 2y ago

> The challenge is how do you revoke a certificate which was used to issue millions of ID cards/passports once it leaks? Does everybody suddenly not have a "valid" ID proof? Revocations always come with a revocation date. Only passports issued after that date would be invalidated. The issuance dates could be proofed with cryptographic timestamps. There is a trade-off between false positives and false negatives when choosing the revocation date of the issuer certificate. With OCSP, you could also revoke all the individual IDs that are not known-good (known to have been issued legitimately). Of course, a world-wide interoperable passport scheme is unlikely to be designed with such an elaborate verification system, and maintaining registries of all legitimate IDs comes with its own risks. In case of a massive breach, it’s more likely that everyone will have to get a new passport and re-prove their identity for that using separate means.

xvilka 2y ago
> In case of a massive breach, it’s more likely that everyone will have to get a new passport and re-prove their identity for that using separate means. If you have a big family with the ownership of many assets - a car, house or an apartment, bank accounts, mortgage, various subsidies, and so on, the number of instances that you need to go to change your old passport data to a new one could quickly grow up to one hundred, depending on a country. The biggest problem with reissuing a passport is that its number and issuance date change, forcing you to jump through many hoops to continue life as before.
- jltsiren 2y ago
  That sounds weird. Which country abuses passports like that? From my perspective, a passport is just an identity document. It's not a source of identity. When you get a new passport, your identity doesn't change, so you don't have to update your information anywhere. Immigration officials may be the main exception, if you live outside the country of your citizenship. Or maybe there is some hassle if you need to transfer a visa to the new passport.
  - Joker_vD 2y ago